The present invention has for object a process and a group of catalysts for hydrodesulfurizing hydrocarbon cuts of high olefin content (15 to 45% of olefins by weight), this hydrodesulfurization taking place with a minimum hydrogenation of these olefins, so as to avoid as much as possible a loss in octane number when the hydrocarbon cut consists of gasoline.
Certain gasolines obtained by catalytic cracking may have, even after extraction or chemical removal of the mercaptans, a too high content of non-acidic sulfur compounds to satisfy the market requirements. This is the case for the catalytic cracking gasolines obtained from vacuum distillates or deasphalted residues of high sulfur content. In that case, the resultant gasolines have a high content, not only of mercaptans, but also of non-acidic sulfur compounds of the sulfide, di-sulfide, thiophene and alkyl thiophene type, which must be at least partly removed without concomitently decreasing the desired octane rating for the resultant fuel.
The conventional hydrodesulfurization catalysts comprising metals and/or sulfides of metals from the groups VIII and VI B of the periodical classification, which have always been used in an atomic ratio (R) such that R=VIII/VI B+VIII is about 0.25 or lower than 0.5, are known as very active for hydrogenating olefins.